"What it looks like is a palm tree, or perhaps a tree fern," said the study's lead author, paleobotanist William Stein at Binghamton University in New York.

"It's a kind of morphology that's instantly recognizable among some modern groups [of trees]," he added.

The bottlebrush-like branches likely used photosynthesis, as most modern plants do, and produced spores, Stein said.

The trunk, found in southeastern New York State, is identical to 385-million-year-old fossilized stumps discovered in the nearby town of Gilboa about a century ago. The stumps represent the earliest known forest.

Until now, however, scientists could only speculate what type of tree the Gilboa stumps, designated Eospermatopteris, represented.

"What we found in the last couple of years was evidence of what the top of these things looked like," Stein said.

The new fossils are described in tomorrow's issue of the journal Nature.

They indicate the fossil trees belong to a previously known plant group called cladoxylopsids, Stein said.

Scientists suspected the fernlike cladoxylopsids were large, but experts never had more than the branches to work with, Stein added.

"What we got here is like a double whammy," he said. "On the one hand, we know Eospermatopteris is these great stumps. On the other hand we have real evidence for how big the cladoxylopsids actually were."